How to get more than three modes on a DX8 and APM 2.5

I'm trying to figure out how to get more than just the three mode selections on my APM 2.5 using a Spektrum DX8. I use ch5 (aux1) to connect to the mode input and since it's a three position switch I get to assign three modes. So how do you get more than that at a time? I'm thinking there's something I do on the radio to allow another switch to alter aux1 output and give me three different pulswidths but I haven't figured it out on my own yet. Any help is appreciated!